It's always scary making a film as I never set anything up or ask anyone to do anything, so I worry that we'll find a story. I have to trust that a film will come out of the journey we embark on. I have many, many sleepless nights.

I watch mainly fiction. The films I like watching are films where you see people change, like with Boyhood. You see a moment in someone's life where it's a breakthrough. For me, the breakthrough in Boyhood is that amazing moment right at the end when he finds somebody he can feel relaxed with, and who will maybe be a friend for the rest of his life. I like that it doesn't end in a love affair or marriage. It just ends in, "Wow, I found people I can relate to for the first people in my life. These people accept me, I like them."

I try to make films where the audience forgets the filmmaking and gets engrossed in the story as it unfolds. I don't want them to ever feel bored, or that they're being told what to think, or to feel depressed. I don't like films about victims - I want to celebrate brave survivors like Brenda and the wonderful women in the film.

I don't have any advice at all. I think we all make the films that reflect the kind of people we are; we all make such different films. There's not just one way of doing it.

I want every scene to feel electric and I try to finish the filming period with a clear trajectory: a beginning, a middle, and hopefully an end.I hate "fly on the wall." It infers that I don't relate to the people we're with and that I don't get affected by events. I like it when people talk to me. I never say things like "Don't look at the camera" - how bossy!

The magic of documentary is that I keep being surprised and amazed by the things I film.

The biggest misconception about me is perhaps that I film all the time and film everything randomly. The truth is I film very little and always when something excites me and seems to mean something for the film.